The stereotype that lung cancer mainly affects men needs to be revised, new study findings show.
While the incidence of lung cancer declined among men from 1992 to 1999, it has simply plateaued among women - a trend that has helped to narrow the gap in cancer rates between men and women, the new report indicates.
“If current trends continue,” he added, “the number of women with lung cancer will surpass that of men within the next 10-15 years.”
Using the National Cancer Institute-funded database to locate men and women who had been diagnosed with lung cancer during the 25-year span from the mid 1970s to the late 1990s, Kalemkerian and his colleagues analyzed information on nearly 229,000 lung cancer patients.
They found that half of the men and women were diagnosed when they were 66 years of age or more, while half were diagnosed at 65 years or younger. About 41 percent of patients diagnosed at 49 years of age or younger were women, however, in comparison to 35 percent of those aged 50 or older, the researchers report in the medical journal Chest.
The reason for the higher percentage of women among younger lung cancer patients is unknown, although some have speculated it may be due to women’s greater susceptibility to the cancer-causing substances in tobacco. Also, Kalemkerian added, “one must always consider the relatively close prevalence of tobacco use in younger men and younger women as a potential reason.”
Overall, the incidence of lung cancer remained higher in men than in women throughout the study period, Kalemkerian and his colleagues report. Yet, fewer men have been diagnosed in recent years while the rate of occurrence among women has remained relatively steady.
At its peak, the incidence of lung cancer among women was 33 cases per 100,000 women per year. From 1992 to 1999, however, that rate plateaued at 30 to 32 cases per 100,000 per year.
Among men, the incidence of lung cancer cases peaked in 1984 at 72.5 cases per 100,000 men per year, and dropped to 47 cases per 100,000 per year by 1999.
Kalemkerian explained that smoking declined among men due to the surgeon general’s warnings in the late 1960s, which led to a great reduction in the incidence of lung cancer 20 years later. “However,” he said, “the prevalence of smoking among women, especially younger women, rose significantly through the 1970s thanks to the changing social status of women and the large-scale advertising efforts of the tobacco industry, such as Virginia Slims ads and athletic backing, that specifically targeted women.”
At every stage of the disease, however, women had a better chance of survival than did men.
This was particularly true when the diagnosis was made in the early stages of the disease, when it could be aggressively treated with surgery. Nearly two-thirds (64 percent) of women with early-stage lung cancer underwent surgery, in comparison to 56 percent of men. In contrast, men with early-stage lung cancer underwent radiotherapy - a treatment usually given to those with limited lung function - more frequently than did women.
“It is very clear that surgery in early stage disease affords the patient the best chance for long-term survival,” Kalemkerian said.
Still, he noted, “over 40 percent of those that are currently dying of lung cancer in the US are women, with nearly twice as many women dying from lung cancer (73,000) as from breast cancer (40,000) every year.”
Lung cancer “is a huge public health problem throughout the world with over 1 million deaths per year” - more than the combined number of deaths from breast, prostate, colon and pancreatic cancer, Kalemkerian added.
“The best way to combat cancer is to prevent it, and 90 percent of lung cancer is preventable,” he said. “However, we will not make any major strides in fighting this disease until our society changes its view of tobacco use from that of an individual right to that of a societal evil.”
SOURCE: Chest, March 2005
Revision date: July 9, 2011
Last revised: by Jorge P. Ribeiro, MD